1. Technical Field
The present invention relates to an ink jet recording method and an ink used for the same.
2. Related Art
An ink jet recording method is a recording method for forming images by attaching ink droplets to a print medium such as paper by means of flying (discharging) the ink droplets. Due to the innovative progress of ink jet recording technologies in recent years, the ink jet recording method has become applicable so far in the field of high-definition printing (image formation) which has been conducted by silver halide photography and offset printing. Therefore, as one of the characteristics required for the ink jet recording method, the responsiveness to printing on various print media having poor ink absorbability, such as film substrates based on polyvinyl chloride and olefin, has become an important issue.
For the ink for the offset printing used in the related art, as low boiling point solvents that have been widely used as organic solvents, aromatic hydrocarbon such as toluene and xylene; aliphatic hydrocarbon such as hexane and kerosene; ketones such as methyl ethyl ketone; esters such as ethyl acetate; propylene glycol monomethyl ether acetate and the like have been used in general. However, when printing is performed on a polyvinyl chloride substrate as a print medium by using the ink including such organic solvents, since these organic solvents have low boiling and flash points and strong odor, the ink is not preferable in terms of an operator's safety. In addition, there is a problem in that nozzles are easily clogged since the ink is dried rapidly, and that print specifications have high costs for reasons of dissolution and swelling with respect to plastic (for example, a polystyrene resin, an ABS resin, and the like) used for apparatuses and components such as ink storage container and a printer. Moreover, when printing is performed on the polyvinyl chloride substrate or the like, printing quality and a drying property of printing are not satisfactory.
Regarding a recording method that forms images on non-ink-absorptive and low-ink-absorptive print media by means of the ink jet recording method, JP-A-2000-44858 suggests a method in which an ink including water, a glycol-based solvent, an insoluble colorant, a polymeric dispersant, a silicon-based surfactant, a fluorinated surfactant, a water-insoluble graft copolymer binder, and N-methylpyrrolidone is printed on a hydrophobic substrate. Japanese Patent No. 3937170 suggests a method in which an ink including an aqueous emulsion polymer having a glass transition temperature of 40° C. to 80° C., a pigment, and a water-soluble surface agent selected from monoalkyl ether of an alkylene glycol, 2-pyrrole, N-methylpyrrolidone, and sulfolane provides images on a hydrophobic surface. JP-A-2005-220352 suggests a polymer colloid-containing ink jet ink to be printed on a non-porous substrate, which includes a volatile co-solvent having a boiling point of 285° C. or less, acid-functionalized polymer colloid particles, and a pigment colorant. Japanese Patent No. 4308526 discloses a non-aqueous ink composition for ink jet recording which includes a mixture of a diethylene glycol compound and dipropylene glycol compound that stays liquid at a normal temperature and pressure in a predetermined mixing ratio.
However, the solvents such as the diethylene glycol compound and propylene glycol compound used in Japanese Patent No. 4308526 are problematic in terms of landing accuracy (discharge reliability).
As the ink used in the ink jet recording method, an aqueous ink results in poor image quality and a fixing property when forming images on a non-absorptive print medium. Accordingly, this leads to a problem that the printing speed and recording method are restricted. Meanwhile, the non-aqueous ink using a high boiling point solvent has a poor drying property, compared to a non-aqueous ink using a low boiling point solvent. Accordingly, this leads to a problem that the printing speed and recording method are restricted, and that the image quality deteriorates.
The problem of image quality mainly results from the drying property of an ink, and the drying property is a factor of the fixing property and tackiness.